Various types of optical fiber cable assemblies have been developed since the inception of optical fiber communications systems. Many fiber optic products incorporate fiber pigtail interfaces between the optical device and the optical connector, collectively referred to as cable assemblies. These fiber pigtails are extremely fragile and must be handled carefully. However, optical systems are subject to mechanical stresses which can damage the systems. In particular, the interface between the fiber optic connector and cable is particularly sensitive to damage arising from the concentration of stress at the connector interface and the weight of the connector body. In certain instances these stresses may be sufficient to cause physical damage to the connector's components and the optical fibers contained therein. Such mechanical stress can distort optical paths and alignment. Damage and misalignment will ruin the fiber's ability to transmit light. And in many cases, can completely disrupt the system's performance.
Thus, it is desirable then to introduce very little mechanical stress on optical fiber end, which in turn promotes long-term life.
To this end, some optical systems use a combination of rigid printed circuit board (PCB) and flexible PCB. A disadvantage of a combination of rigid PCB and flexible PCB is that a rigid/flexible PCB is more expensive compared to rigid PCB only. The approximate cost ratio is 20:1. Further, a flexible PCB with thin track widths (100 μm and below) is difficult to process with guaranteed quality.
Another problem experienced by optical systems is the interconnection of the optical assembly to the PCB board itself. It is also known in the art to use a separate electrical contact (metal connector leads integrated in a non-electrically conductive material). A disadvantage with a separate electrical contact is extra cost for additional piece parts as well as additional solder joints having a negative impact on signal integrity performance.
It is also known in the art to use an external assembly of mechanical alignment features and/or active alignment of optical dies and/or lens system. Disadvantages with an active alignment procedure for optical die/lens system include: high precision alignment tooling and/or machinery needed and extra cost for additional piece parts.
Complicating things even more is the desire for increasing the number of fibers presented in a single optical connector. The industry is evolving from single fiber ferrules to multi-fiber ferrules containing two or more fibers.